Modeling of pulsed laser guide stars for the Thirty Meter Telescope project

TL;DR

This paper models the response of mesospheric sodium atoms to pulsed laser formats for the Thirty Meter Telescope's laser guide star system, comparing their effectiveness to continuous-wave lasers in achieving required photon return flux.

Contribution

It provides a detailed atomic physics and light-atom interaction model for pulsed lasers in LGS applications, demonstrating their potential to meet TMT specifications.

Findings

Pulsed lasers can achieve photon return comparable to continuous-wave lasers of the same average power.

Modeling includes effects of geomagnetic field and atomic collisions on sodium atom response.

Both laser formats can satisfy TMT's photon return flux requirements.

Abstract

The Thirty Meter Telescope (TMT) has been designed to include an adaptive optics system and associated laser guide star (LGS) facility to correct for the image distortion due to Earth's atmospheric turbulence and achieve diffraction-limited imaging. We have calculated the response of mesospheric sodium atoms to a pulsed laser that has been proposed for use in the LGS facility, including modeling of the atomic physics, the light-atom interactions, and the effect of the geomagnetic field and atomic collisions. This particular pulsed laser format is shown to provide comparable photon return to a continuous-wave (cw) laser of the same average power; both the cw and pulsed lasers have the potential to satisfy the TMT design requirements for photon return flux.